Electric pneumatic casting machine



June 24 1924.

C. S. VAN HORN ELECTRIC PNEUMATIC CASTING MACHINE 2 Sheets-Sheet 1 FiledJu ly 27, 1920 June 24 1924. 1,499,132

C. s. VAN HQRN ELECTRIC PNEUMATIC CASTING MACHINE Fil d u y 27. 1920 2Sheets-Sheet? Patented June 24', 1924.

TED STATES,

1,499,132 PATNT orrics;

CHRIS s. VAN HORN, or BLOOMSBURG, PENNSYLVANIA.

ELECTRIC PNEUMATJEC CASTING MACHINE.

Application filed July 27,

' paratus used iii-connection with my process for producing dentalinlays of exact dimensions.

Up to the present time, no apparatus has been devised for the accuratecasting of dental inlays, that is, dental castings of the same marginaldimensions as the wax pattern in the tooth. The methods and apparatusnow in use are at best, only approximate, mainly because no cognizanceis taken of the fact that the materials which enter into thecastingoperation, such as the gold, the investment materials, and the patternwaxes, are subject to the physical law of expansion and contraction uponthe appli-- cation and withdrawal of heat, each such substance havingits individual coefficient under varying thermal influence.

For instance, in all known processes, no exact allowance has been madefor any change in size in the wax pattern occurring in transferring itfrom the mouth to the investment. Pattern wax is very susceptible to thephysical effect of heat, a rise or fall of a few degrees in temperatureduring the hardening or setting of the investment involving' thepattern, means a corresponding change in the size of the wax mass andconsequently the casting cavity or mold. So also, during the drying outand burning'out operations the investment expands when heated to suchhigh temperatures as 1,000 F., which expansion produces a correspondingincrease in the size of the casting cavity. An accurate process demandsnot only that the investing apparatus used be capable of not onlyimparting through the plastic investment a given temperature to the waxpattern during the investment and maintaining this definite temperatureuntil the investment is thoroughly hardened, but also that the castingapparatus be capable of imparting to the investment which forms thecasting mold, a predetermined elevated tem- 1920. Serial No. 399,365.

perature whereby to slightly enlarge and maintain at such size, thecasting cavity in the investment during the drying out, burning out, andeven during the initial portion 1 of the actual casting operation. Thistemperature regulation must be accurate, and at all times under theabsolute control of the operator.

To make a gold casting of the same marginal dimensions or size as thewax pattern, when the latter is in the tooth cavity in the mouth, thewax pattern must be invested at a temperature sufficiently above toothcavity temperature (which is approximately 95 F.) to compensate for theshrinkage in the gold casting during its cooling.

Present pattern waxes of the best quality can not be safely expanded inexcess of about two per cent without melting or dulling delicate orsharp margins of the pattern, and investing materials of the bestquality have a maximum expansion of 0.85 per cent at around 1000 F.Above this they shrink that is, burn smaller, and if permitted to cooldown from 900 to 70 F., they shrink, and the mold is smaller than whenthe investment set. On the other hand, the total shrinkage in 24 K. goldis around 3.84 per cent, which can be partly controlled by pressure,when casting, but the uncontrollable shrinkage in gold when cast underhigh;

pressure is 2.20 per cent. Hence, in order to neutralize all thisuncontrollable shrinkage in the gold, that is, 2.20 per cent, some meansother than the expansion of the pattern must be used. The expansion ofthe investment when heated to dry out and burn out the wax is availedof. Minimum gold shrinkage (220 per cent) minus maximum wax expansion (2per cent) leaves 0.20 per cent shrinkage to be neutralized through the1nvestment expansion which is 0.85 per cent maximum.

The most rational technique is therefore to utilize the maximumexpansion of theinvestment without disintegrating it by maintaining themold, and hence the contained investment at an elevated temper-. ature'during the drying out and burning out periods, and to supplement thisexpansion with a correspondingly less than maximum expansion of the waxpattern during the'investing, process, softhat these combined expansionsof the pattern wax during investing and the expansion of the investmentduring drying out and burning out, produce a mold or casting cavity ofjust I the right size so that'the gold cast therein will on cooling,contract to the same marginal dimensions as the original wax patternwhen in the tooth cavity in the month.

By a series of experiments and calculations, taken in connection withthis meth 0d of casting, it has been found that the wax pattern shouldbe mantained at an approximate temperature of 115 F. during theinvestment operation, and that the investment, should .be subjected teamaintained temperature of about 900 F. during the drying out, theburning out and initial part of the casting into temperature.

This method thus takes into consideration the individual contractionsand expansions of the pattern, of the investment and of the gold castingduring the process of. making the dental inlay, and by controlling theheating etl'ects throughout the entire process, produces a casting ofthe required marginal dimensions.

Inasmuch as the present invention relates solely to the castingapparatus used in connection with the above process, no further mentionof the investment apparatus will ture conditions.

The 'main object of this invention is to provide a mufiie and flaskmechanism constructed and arranged to suitably control the temperatureof the investment during the drying out, and burning out and castingvoperation.

Another object of the present invention is to provide a device of thecharacter described which comprises a flask seat and a suitably heatedmutfle, together with means for shifting the mufiie and seat relativelyso that the seat supporting the flask With its contained investment canbe moved within or without the muffle. I

Still another object of this invention is to provide a device of thecharacter described which includes an electrically heated muffle, aflask seat carriage movable Within the muffle chamber, together withmeans for controlling the heating effect of said muflle and regulatingthe temperature thereof at any instant.

Still another object of the invention resides in providing a device inwhich the flask seat in moving outside of said mullle chamberautomatically acts to alter the heating effect of the muifle.

Still another purpose of this invention is to provide an in'iprovedmuflle for a device of this character in which the inullle is formedwith an open chamber around the inner walls of which is arranged aheating coil, the muflie being constructed so that the flask seat in itsmovement within the muflle will take a position so that the heatingwires will entirely surround the same.

A further object of this invention is to provide a muflle of improvedconstruction for use in the above mentioned arrange ment.

A further object of this invention resides in providing a novelarrangement of a mut fie, and flask seat carriage adapted to move theflask seat supported thereby into the mutfle chamber, the flask seatcarriage and flask seat being suitably vented to permit the escape ofgases and other matter during the drying out and burning out operations.

Still another object of this invention relates to the specificconstruction of the flask seat itself.

' Another aim of this invention is to provide a novl combination andarrangement of muflle, flask seat and its supporting means, and flaskseal mechanism whereby the flask seat supporting means withits flask andcontained investment may be shifted from a position within the muflieinto contact with the flask seal mechanism.

Yet another object of this invention coniprises the means forautomatically locking the flask seat supporting the flask and containedinvestment in contact with the flask seal.

A further object of this invention resides in providing a flask seat'andflask seal with means for shifting said seat and seal relatively,whereby to contact the flask on'the seat against the seal, together withmeans for locking the said parts in such position. and means foradmitting fluid pressure to the investiment within the flask during thecasting operation.

A further object of this invention resides in the means whereby therelative movement between the flask seat and seal control the airpressure admitted to the investment in Another feature of the inventionresides in the novel construction of the upper edge of the flask whichis adapted to contact against the seal mechanism to maintain anReferring more particularly to the accompanying drawings:

Figure 1 illustrates a perspective view of the entire machine;

Fig. 2 is a fragmentary sectional view illustrating particularly themuffle, the flask seat mechanism, and the flash seal;

Fig. 3 is a sectional detail of the sprue;

Fig. 4 is a bottom view thereof, and

Fig. 5 is a detail sectional View of the flask seat.

Broadly, the invention comprises the supporting standard on which ismounted a muffle provided witl a preferably vertically arranged borether hrough, the inner walls of which are formed with heating coilsentirely around the same, with electrical con nections to athermo-electric couple and the usual pyrometer which is also mounted onthe base. The heating effect of the muffle is controlled by means of theusual rheostat likewise mounted on the base. Vertically movable throughthe axis of the muffle bore is arranged the flask seat carriage adaptedto support the flask seat, on which is placed the flask with itscontained investment, so that when the flask'is lowered into the muflle,it will be entirely surrounded by the heating coil. Arranged in spacedrelation to the end in line' with the bore of the muffle is a flask sealmechanism provided with suitable connections to a source of preferablycompressed air, and the arrangement of the mufl'le, the flask seat andflask seal is such that the flask seat may be shifted from a pointwithin the mufllc chamber into sealed contacting position, the apparatusbeing constructed and arranged so that when in this latter position, theflask seat is locked against shifting movement and air pressure isadmitted from a tank into contact with the investment within the flask.

Referring more particularly to the accompanying drawings, there isprovided the usual base 1 of suitable insulated material, upon which ismounted by means of the standards 2, 3, a suitably formed support 4, tothe front end of which is preferably removably attached a muflle 5. Asshown. more in detail in Fig. 2, the forward end of the supporting base4: is provided with a suitable upstanding flange 6 within which ismounted a bushing flange a tubular support 7, which flange, togetherwith the flange 6, forms a support for the mufiie. While the mufl'le maybe of any desired shape, and construction, the preferred form comprisesan annulus of suitable heat resisting material v8 around the innerperiphery of which is continuously wound a heating coil 9, the upper andlower loops of which are suitably embedded in the upper and lower endwalls of the annulus 8 by means of any desired fastening means 10. ;Thebase and top end caps 11 and -12 are provided for covering the exposedends of the annulus and winding. As shown in the drawings, these caps 11and12 are suitably cut away as at 13 to clear the winding wires. Theupper cap 12 is provided with a central beveled mouth 14 terminating ina projecting lip 15 which forms a suitable opening for the entrance ofthe flask into the muffle chamber. The base cap ll is likewise cut awayand is provided with a central bore 16, the walls of the cap at thispoint being suitably conformed to provide a supporting surface for themuflie to seat itself upon the upstanding flanges 6 and 7 If desired, anadditional'bracket may be provided as at 17 for' attaching the muffle toanupwardly projecting standard 18, which in the present case, is shownas integral with the support 4 on the base. The muflle is providedwith athermo-electric couple 19 and with suitably insulated connections 20 tothe pyrometer 21, illustrated in Fig. 1, which at all times records thetemperature of the heating coil. The heating effect in this coil iscontrolled by the usual rheostat' mounted pref-' erably on the base 1including the movable arm 22 making contact with a series of re- Isistance contacts 23. The machine is adapted to be connected to anexternal source of current connected to one contact 22' and to the othercontact 23 of the knife switch 24: so that by manually opening andclosing thisswitch, current to the machine is out out or in. In additionto this manual control cut off, there is arranged an automatic cut offcomprising an arm 25 attached ,to the base of the flask seat carriagehere inafter described and adapted to be raised by the elevation of theflask seat carriage to throw the knife switch 2 1 and break theconnection.

The investment contained 7 Within the flask is adapted to be heated tothe desired temperature by means of the muflle and in order. tointroduce the flask within the muflle, there is provided a relativeshifting movement between the flask carriage a'nct muffle. The preferredconstruction for accomplishing this function is shown in the presentapparatus, in which the forward part of the base 4 is provided with avertical bore 24 concentric with the axis of the muflle and theupstanding flanges 6 and 7. Movably mountgtl within this bore isarranged a flask seat carriage, preferably in the formof a plunger 25provided along its inner lower extremity with the gear teeth 26(see'Fig. 1), meshing with a pinion 27 mounted on a shaft 28 havingbearings 29 and 30 depending from the under side of the base 4. Theouter extremity of the shaft 28 is provided with a suitable handle 29for giving oscillation to the shaft to raise and lower the flask seatcarriage.

The flask seat 31 for supporting the flask flask seat 31 which isprovided with a tubular shank 33 and a laterally extending annularsupporting surface 34 formed with an upstanding flange 35 to form asupport-- ing rim fitting snugly within the free end of the flask 32.This upstandingrim is adapted to seat a wafer of porous material for apurpose hereinafter described. This rim 35 is provided with verticalslits 3.5

therearound to permit the escape of thegases from within the flask andlikewise the base 34 of the seat is provided with suitably formed vents36, and for the same purpose, the shank 33 is provided with a centralbore opening on to the supporting surface of the base 34. If desired,the hollow shank 33 may be provided with suitable additional vents 37for a similar purpose sothat when the shank 33 of the flask seat isfitted within the hollow end of the carriage 25, and the flask with itscontained investment is seated on the flask seat, with- 1 in the muflle,and the heat generated to burn outthe wax pattern within the investment,the gases, smoke and moisture from the pattern "can escape through theporous insert in the flask seat, throughthe vent slits 35 in theupstanding rim- 35, through the perforations 36 in the base 34, throughthe bore 38 of the shank 33, and through the vents 37 into the hollowend of the plunger 25, which is also provided with suitable vents 39 forthe discharge of these gases, outthrough an opening 40 in front of thesupport 4. 7

Arrangedabove the muffle 5 and in axial alinement therewith, is a flaskseal mecha nism. This mechanism is preferably supported on the standard18 and comprises a chambered sealing head 42 secured on the standard 18and overhanging the mufile. Movably mounted Within the chamber 43 on thelower portion of the base 41, is a flask seal comprising a plunger 44formed with an enlarged annular face 45, peripherally threaded toreceive a flange 47 adapted to hold in place a yieldable packing orflask contacting member 48 which is composed of suitable materialcapable of forming an air tight seal with the upper rim of theflask,which as shown in detail in Fig. 3 is provided with an annular roundedbead 75, which not only insures an air-tight joint at this point, butprevents the packing 48 from being cut by the pressure of the lockingmechanism hereinafter described. The plunger 44 is provided with acentral bore and projecting nozzle 46 forming an air outlet, The innerend of plunger 44 slides within the chamber 43 in the head 41, and

the inner hole of the head 41. This plug51 is likewise provided with acentrally arranged bore 52 forming an air conduit in axialalinement'with the air conduit 45 and connecting chamber 43 with anupper chamber 53 in the upper portion of the head 41. This chamber 53 isprovided with a suitable connection 54 to a source of air or fluidpressure 55. The connection between the ,air conduit 52 and chamber 53is controlled by an air valve 56 provided with a preferably integralstem 57 sliding in a bore 58 formed in a cap 59 threading into the outerextremity of the head 41. A suitable spring-60 normally seats thisvalve. Projecting through the threaded plug 51 is an adjustable push rod61, the upper end of which contacts firmly against the under face of thevalve seat, while the lower end of this push rod 61 is provided with anadjustable threaded connection 62 with a similarly threaded inner faceof the plunger 44, said connection being suitably; ported as at 63 topermit the passage therethrough of the compressed air. The flasksupported on the flask seat in its movement upward, contacts against theflask seal to slightly move the same, thereby admitting compressed airinto the flask, and in connection with this construction there is alsoarranged mechanism for positively and automatically locking the flaskseat in this raised seal contacting position. This last named functionis accomplished by providing the lower portion of the carriage orplunger 25 with a suitably formed slot- 64 adapted in the raised posi-.

tion of the carriage to come abreast of a locking member 65 slidablymounted within the bore 66 in the support 4. As shown in Fig. 2, thislocking member 65 is surrounded by a spring 67 coiled'between anabutment 68 on the locking member and the cap 69 secured to the base sothat the spring tends to force the locking member 65 into the slot 64when in alinement therewith. In order to retract the locking member 65,the same is provided with teeth 70 at its outer end gearing with apinion 71 on the shaft 72 controlled by an oscillatable lever 73. Inorder to retain the plunger 25 with its slot in suitable alinedposition, a key-way 74. is provided on the base of the plunger 25adjacent the plunger, so that when the plunger is in loweredposition'the locking member .65, will project slightly into the key-way74 to act as a spring pressed retaining means to hold the plunger 25 inany shifted position. The lower face of this key-way is provided with agradually sloping surface so that the locking member 65 will be forcedfreely backwardly on the further elevation of the carriage 25. 'lVhenthe flask on the flask seat is raised into contact with the flask seal48, it is thereafter necessary to make this contact air-tight, so thatthe air pressure thereafter admitted through the seal into the flaskwill not escape and to accomplish this, it is necessaryto securely lockthe flask seat against downward movement prior to the introduction ofthe air pressure. In order to accomplish this, the upper face of thelocking member 65 is provided with a cam surface 65' which, when thelook- 'ing member is projected into the slot 64:, acts to give theplunger 25 an additional lifting movement into extreme upper position,at which time, the locking member 65 has passed entirely through slot.64 under the action of the spring 67. This additional upward movement ispermitted by the yielding movement of the plunger 44 of the sealinghead. i

The special form of sprue used in con- ,.nection with the improvedprocess set forth in this application is shown in Figures 3 and 4. Inthis connection, the sprue comprises a base 7 6 provided with an annularflat lateral rim 77 and an inner upstanding flange 78 adapted to fitexactly within the inner periphery of the flask as therein shown, theend of the flask resting on the annular supporting surface 77. Theupstanding flange 78 is integral with a central conical projection 79formed with a 'longitudinal bore 80. The base is likewise provided witha plurality of'spring fingers 81 which project laterally from the planeof the surface 77 to engage the outer periphery of the flask 32 wherebythe same is held se-' curely between the spring fingers 81 and theupstanding flange 78, the end of the flask being as before stated,supported permanently on the seat 77 These fingers 81, of which theremay be three ormore, are secured to the base member by means of athreaded cap 82 screwing into a suitable recess 83 in the base.Obviously, other modes of forming these fingers and attaching them tothe base may suggest themselves. Longitudinally within the central bor80 of the base is a sprue wire 84: which, as shown in the drawings, isadapted to hold the wax pattern 85 in proper position within thecontained investment 86. Means is provided for holding this sprue wirein adusted position, herein shown as a threaded member 87 passingtransversely through the threaded cap 82 and engaging the sprue 84:.This adjusting member 87 is provided with a thumb piece 88 to facilitateits turning.

For a complete understanding of the present invention, it is explainedthat after the ,pattern is formed in the usual manner and placed on thesprue 84, and after the investment material has been A mixed,

are subjected in the investing apparatus to a maintained temperature ofapproximately one hundred and fifteen degrees F. The pattern is nowquickly given the usual preliminary coating and is then placed in theflask to the proper depth by means of the adjustable sprue 84, and theinvestment introduced around the pattern care being taken to provide auniform temperature throughout the entire investment process. While itmust not be overlooked that when the investment is being poured into theflask and when the pattern is coated, a change in temperature takesplace. This change, even though pronounced, is corrected by employing aslow setting investment which does not begin to stiffen under fiveminutes or more from the time when it is pouredinto the flask, thusallowing ample time for it to regain the loss and impart to the wax thedesired determinable temperature, the ultimate desideratum being thetemperature of the Wax during the setting of the investment.

Theflask having remained for possibly one-half hour at a constanttemperature, the investment hasthen hardened sufficiently to resist anychange in the size of the pattern vdue to change in temperature, and sois transferred after removing the sprue and smoothing the crucible inthe usual way to the casting apparatus which forms the subject matter ofthe present invention for the drying out, the burning out, andthe'casting operation.

Thefiask with its contained investment having been placed upon the flaskseat in the casting machine, and lowered into the electric muflie 5 byrotating the hand lever 29 counter-clockwise, the electric current isthen turned on by closing the switch 24,v the rheostat control lever 22being on the proper contact. By means of the thermoelectric couple whichis in the muffle chamber, and connected to the'pyrometer, the degree ofheat which is generated in the muifie is recorded on the pyrometerscale, and by means of the rheostat, the temperature of the muflle isunder complete control so that the drying out and burning out operationsmay be completed at the exact temperature demanded. 1

After this operation, the temperature is raised to the desired degreefor a suflicient length of time, a given quantity of gold metal is thenplaced in the ingate and is then very quickly brought to the desiredstate of liquefaction by the direct application of an oxyhydrogen jet.Prior to this heating the lever 29 is shifted clockwise to lift theflask out of the inufile, and during this upward movement, the finger25'on the base of the plunger 25 has struck the knife switch 24 to breakthe electric circuit to the heating coil so that thereafter the gold inthe ingate is heated solely by the oxyhydrogen jet. At the moment thebead 75 on the top of the flask seat 32 contacts w1th the flask seal 48,the lowest point on the top face of locking key 65 is' in register withthe upper edge of the slot 64 in plunger rod 25, hence the compressionspring 67 is free to act so that the cam face 65' of the locking member65 under actuation of the spring forces the flask and flask seal base.48 and flask seat upwardly until the flask seal base plunger 49 meetsthe fixed packing 50. Just a fraction of a seco d after the seal headstarts to move the 1 lve, the push rod 61 contacts with air valve 56 andlifts it off its seat, thus admitting compressed air through thepassages 45, 63, chamber 43,

conduit 51, chamber 53, and inlet 54 into the flask and the ingate andforcing the'fluid metal into the-mold in the investment. The forceexerted by the cam face 65' of the locking pin actuated by the spring 67against the top of slot v64, is transmitted through carriage 25, thusautomatically establishing an air-tight union between the bead 5 on theflask 32 and the flask seal 48 to securely lock the moving parts in thatfixed position.

After the metal casting has crystallized, the flask is released byturning the lever 29 clockwise and the locking pin 65 is withdrawn bymeans of the oscillation of the handle 73 after-which the flask mayeasily be lowered to any desired position by turning pinion 27 by meansof the handle'29. Furthermore, the front face of the tapered locking pin65 when not in slot 64 engages with the key-way 74 on the carriage 25,and while the carriage 25 may be easily raised or lowered to anypositiondesired other than. that to the position of the flask 'contacting withthe sealing'mechanism, it willremain automatically at that particularposition for the reason that the end of the locking pin is forced by thespring 67 against the key-way of the carriage.

It is also obvious that many changes in I the details of the.construction and the arrangement of the parts may be made withoutdeparting from the spirit of the invention as set forth in the appendedclaims.

Having thus described the invention, what I claim as new and desire tosecure by Letters-Patent, is-- I 1. An electric pneumatic castin machine-com rising a base, an electrical y heated .mu e thereon, a-flask sealmounted on said base adjacent said muflle, means providing a source ofair pressure for said seal, a flaskelectric couple and pyrometer mountedon said base and electrically connected to said I ling the muflleheating circuit. 2..An apparatus of the class described comprising asupport, an open-top muffle mounted thereon, a flask seat on said support adapted to receivea flask and its contained investment, meansconstructed and arranged to shift said mufile and seat rela tively toposition said flask either within or without said muflle whilemaintaining the investment constantly accessible.

3. An apparatus of the character described comprising a support, amuflle mounted thereon, means for controlling the temperature of saidmuflle, a flask seat mounted on said support adapted to seat a flask andits contained investment, means for relatively moving said seat andmuflle to position the flaskwithin or without the muflle and means forautomatically holding said muffle and seat in relatively shiftedposition. V i

4. An apparatus ,of the character described compr'isinga base, anopen-end muf- -fle mounted thereon with the open end uppermost, a flaskseat mounted on said base and adapted to support a flask with itscontained investment, and means projecting through the lower end of themuffle for raising and lowering said flask into and out of said mufllewhereby said invest- -ment is constantly accessible.

5. An apparatus ofthe character described comprising a base, a mufflethereon, means for heating saidmufile, a flask seat mounted on saidbase, adapted to support a flask with its contained investment, meansfor moving said flask seat and muflle relatively, and means acting at acertain period in said movement to control the effect of said heatingmeans.

6. An apparatus of the character described comprising a base, a mufllethereon, means for heating said muflle, a flask seat on said baseadapted to support a flask with its contained investment, means formoving said seat within and without said muflle, said means acting tocontrol said heating effect when said flask seat is moved away from saidmuflle.

7. An apparatus of the class described comprising atubular support, anopenended muflle mounted thereon, a flask carriage shiftable throughsaid tubular support, a flask seat on said carriage for supporting aninvestment, and means for shiftmg said carriage to position said flaskseat within and without said muflle.

8. An apparatus of the class described,

comprising a support, a muflie mounted thereon, a flask carriageshiftable on said support, a flask seat on said carriage, meansforshifting said carriage, and a spring pressed detent normally engagingsaid carriage to hold the same in shifted position.

9. A device of the character described comprising a tubular support, anopenendcd muflle mounted thereon, a tubular flask seat carriage slidablymounted within said support and movable axially through said muffle, anda tubular flask seat detachably nesting in said tubular carriage, saidseat, carriage and support being suitably vented to permit the escape ofmoisture, gases and smoke therethrough.

10. A device of the class described comprising a support, an open-endedmuflle mounted thereon, a flask seat carriage disposed axially of andshiftable through said support, a flask seat detachably connected to theupper end of said carriage and adapted to support a flask with itscontained investment, and means for raising and lowering the flask seatinto and out ofthe muflle.

11. A device of the class described comprising a ventilated support, anopen-ended muflle mounted thereon, a flask seat carriage disposedaxially through said support, a vented flask seat disposed in the upperend of said carriage, said carriage having a suitable number of ventscommunicating with the vents of said seat, and means for raising andlowering said seat with respect to said 12. A flask seatfor a device ofthe character described comprising a hollow vented shank having alaterally disposed disk-like support, said disk having an annularupstanding flan'ge adapted to engage the walls of said flask, the boreof said shank connecting with the faces of said disk, said disk andflange also having a suitable number of vents.-

13. A flask seat comprising a tubular shank vented and formed at itsupper portion with a lateral disk having an annular upstanding flangeadapted to form a seat for the flask, said flange and the upper face ofsaid disk being suitably vented, the upper face of said diskcommunicating'with the bore of said shank and a substantially thin diskof porous material superimposed on the upper face of said disk and lyingwithin said flange.

14. A device of the character described comprising a support, anopen-ended mufiie mounted thereon, a flask seat carriage mounted on saidbase below said muflie and movable axially therethrough, a flask sealsupported by said base and arranged above and axially of said muflle,and means for shifting said flask seat from a position within saidmuffle to flask seal contacting position.

15. A device of the class described comprising a base, an open-endedmufiie supported thereon, a flask seat carriage and a flask sea]supported by said base and located axially of said nuiflie below andabove said muflle, respectively, means for moving said carriage intocontact with said seal.

16. =An apparatus of the character described coin 'irising a base, aflask seat and a flask seal supported thereon, means for shifting saidseal and seat relatively whereby the flask on said seat and the sealcontact, automatic means for locking said parts in such position.

17. An apparatus of the character described comprising a base, a flaskseat and a flask seal supported thereon, means for shifting said seatinto yielding contact with said seal, means for giving said seat andseal an additional shifting movement whereby said flask is locked inseal engaging position, and means controlled by the yielding of saidseal for altering the air pressure in said sealed flask. i

18. An apparatus of the character described com-prising a base, a flaskseat and a flask seal supported thereon, means for shifting said seatwith its supported flask into contact with said seal, means for givingsaid seat an additional shifting movement wherebysaid flask is locked inseal engaging position, said additional movement acting to admit fluidpressure into said flask for the purpose set forth.

v 19. An' apparatus of the character described comprising a-base, aflask seat movably mounted thereon, a flask seal yieldably mountedthereon and constructed and arranged to be moved by said flask seatmoving means into a non-yielding position, and means brought intooperation by said yielding movement of said seal for locking said seatagainst further movement.

20. An apparatus of the character de-.

scribed comprising a base, a flask seal mounted thereon, a flask sea-tformed with a slot carriage, means for moving saidcarriage toward saidseal, and a spring actuated locking member operable to enter saidscribed comprising a base, a flask seat mov-- ably mounted thereon, aflask seal yieldably mounted against a rigid abutment on said base, saidseal having a fluid pressure inlet,

a valve therefor, and means for moving said seat with the flasksupported thereon into contact with said seal whereby said seal isshifted and said valve is opened to admit fluid pressure to said flask.

23.1An apparatus of the class described comprising a support, a mufllemounted thereon, a flask carriage shii'table on said support, a flaskseat on said carriage, means for shifting said carriage, a springpressed detent normally projected into the path of said carriage, saidcarriage having a slot therethrough to receive said detent whereby tolock said carriage in desired position.

24. A device of the class described comprising a base, an open-endedmufile sup- -ported thereon, a flask seal supported on said base inspaced relation to one open side of said muflie, a flask seat carriagesupported on said lease and movable from a heating position Within saidmuiile to a flask contacting position outside of said mufiie.

25. A device ofthe class described comprising a/support, an open-endedmuflle thereon, a flask seal on said support and spaced from the openend of said muffle,

and a flask carriageshiftable on said support from a position betweensaid muffle and seal into heating and sealing positions, respectively.

26'. An apparatus of the character described comprising a base, ayieldable flask seal thereon, means controlled by the yielding ofsaid'seal for altering the working pressurein said seal, a shiftableflask carriage provided with a locking slot, means for moving saidcarriage to shift said flask into contact with said seal, a springpressed tent being constructed and arranged to give said carriage anextra movement toward said flask seal to operate the pressurecontrolling mechanism.

27. In a device of the character described, a support, a shiitable liaskseal thereon, fluid pressure controlling means operated by the shiftingof said seal, a movable carriage having a groove and a slot therein, aflask seat thereon, means for moving said carriage, a spring presseddetent normally projected into said groove and adapted to enter saidslot on movement of said carriage, and means for retracting said detent-28. In a device of the character described,

a support, a shiitable flask seat thereon, a

shiftable seal thereon provided with an air passage, a spring pressedvalve in said passage normally closing the same, a source of airpressure connected to said passage, said valve and seal beingconstructed and-arranged so that on movement of said seal said valvewill shift to open said passage.

29. In a device of the character described, the combination of a supportincluding an overhanging arm, an open-ended muflle on said support. aseal on said arm overhanging said muflle, a flask seat carriage carriedby said support and shifta'ble axially through said muffle into contactWith said seal. and means on said support for shifting said carriage. Intestimony whereof, I aflix my signa- -ture.

CHRIS s. VAN onu.

